Des Moines, IA: The Great Perennial Divide
- Subject: [cg] Des Moines, IA: The Great Perennial Divide
- From: Adam36055@aol.com
- Date: Sat, 23 Apr 2005 14:02:01 EDT
Central Iowa gardeners may donate their extra plant sections to a Des Moines
program that matches divided plants with schools, neighborhood groups and
community organizations wanting to beautify their grounds.
This year's Great Perennial Divide will be May 14. Gardeners may drop off
their donations from 9 a.m. to 1 p.m. that day at the Des Moines Botanical
Center, 909 Robert D. Ray Drive, and the Urbandale Hy-Vee, 8601 Douglas Ave.
1,700 plants were collected and donated last year, Teva Dawson said, and a
variety of perennials are welcome.
People who cannot donate May 14 may arrange for plant pickup. Call (515)
323-8907 for more information
Divide and Conquer: Separating plants creates more blooms, better health
By Melanie Lageschulte
Des Moines Register Staff Writer
April 23, 2005
Knowing the pluses and minuses of dividing perennials can help gardeners
avoid separation anxiety when it's time to split their plants into healthier,
Plants that are properly separated and transplanted produce more flowers and
build stronger root systems. The process includes digging up crowded plants,
untangling their roots and separating the plants into sections.
Dividing helps gardeners "make room for other plants or keep them
manageable," said Teva Dawson, community gardening coordinator for the city of
While the process appears to be simple - grab a shovel or gardening fork and
dig in - experts caution that not all perennials' dividing needs are equal.
Even common plants, such as irises, peonies and hostas, have their quirks.
"There's no one answer," said Richard Jauron, a horticulturist for Iowa State
University. "Not everything can be divided successfully."
Jauron said plants should not be divided during their peak blooming season.
In the spring, gardeners get a green light to tackle plants that won't flower
until late summer or early fall. But keep the spades away from early flowering
plants, Jauron said, until late summer.
Some plants should be divided every few years to maintain their health. Other
varieties are more flexible and can be left alone until the plants begin to
crowd each other, show faded foliage and produce fewer flowers.
Jauron said some plants, such as garden peonies, should generally not be
divided. Too-small peony plants may not bloom for two or three years, he said.
contrast, bearded irises, with their tendency to spread quickly and thickly,
should be separated every three to four years. "If we don't dig and divide
periodically, they take over," Jauron said.
Kelly Norris' family owns and operates Rainbow Iris Farm near Bedford. Irises
that are not regularly divided, Norris said, lack proper drainage and are
more likely to spread disease among themselves. "You want to give them their
space," Norris said.
Norris suggests gardeners use their hands to start digging dirt away from the
roots of irises or other plants. A potato fork is a good tool to draw the
irises' complex root systems up and out of the ground.
Using potato forks puts less stress on the plant, Norris said. "It's much
easier than just whacking it with a spade." The plant's roots can then be
separated by hand or with a knife.
Some plants, including hostas, do not need regular dividing to maintain their
health. "It's a big misconception," said Joyce Flies, who lives near Dallas
Center and maintains a hosta landscape of about 3,500 plants from 1,200
Hostas can handle separation, Flies said, if gardeners want to share the
plants with others. Otherwise, "if you have a plant that is doing well and has
plenty of room, you don't need to divide it."
Flies said she divides hostas in the early spring, when the plants just begin
to peek out of the ground. Separating them later in the growing season can
harm the plants' showy leaves.
If she needs to split a hosta later in the year, Flies said, she ties up the
plant with nylon or old pantyhose before getting started. The fabric won't
break or damage foliage, she said.
Completing a successful divide means following basic transplanting formulas,
Jauron said, including "just putting them back in the ground as soon as
Jauron said gardeners must set the trimmed-down plants out in a site with the
proper amount of sun or shade and water them more frequently until the roots
are re-established. The new plants should not need additional amounts of
fertilizer, Jauron said. "That's not critical - the water is."
Perennials are divided to control plant size, rejuvenate older plants or
provide additional sections for transplanting. Digging up the plants,
their clumps and transplanting them untangles tightly woven root systems,
plants room to grow and encourages more blooms.
When is it time to divide?
Some plants should be divided on a schedule of every two, three or four
years. Many others can be left alone until the plants show distress - such as
overcrowding, fewer blooms and discolored leaves.
Perennials that should be divided in the spring need to be separated as the
first new growth is seen. Many perennials divided from mid-August into
September must be mulched in November to protect them from winter's chill.
mulch in early April.
Hostas do not need to be divided to keep the plants strong. Ornamental
grasses need separation if the core of the plant appears dead while the outer
continue to thrive. Grasses should be divided in spring or late summer/early
How do I do it?
Water plants well a few days before you plan to divide. Choose and prepare a
new location for the additional sections before you begin. Clemson
University's extension office recommends pruning plants' stems and foliage to
a height of
six inches before dividing them. This makes the plants easier to handle.
Carefully remove dirt from around the plant's base, then use a shovel or
potato fork to dig into the ground about six inches - or more - out from the
of the plant. This helps maintain the plant's root system.
Bring the plant out of the ground and gently shake off excess dirt. Discard
weak or small sections. Separate the roots with your hands or a knife, making
sure to leave each new section with some fresh growth and roots. Put the
plant back in the ground and transplant the new sections as soon as possible.
Dividing techniques vary based on a plants' type of root system:
b" Spreading roots ( asters, purple cornflowers ) - slender roots with no
distinct growth pattern. Divide into clumps of three to five healthy shoots
Discard the center section if it appears unhealthy.
b" Clumping roots ( hostas, day lilies, many ornamental grasses ) - thick
roots radiating out from a central section. Break apart the crown, which is
thick area between the roots and the stems, using a knife if needed. Or pry
apart with back-to-back digging forks.
b" Rhizomes ( bearded irises ) - large stems growing horizontally at or above
the soil level. Trim or discard old or damaged rhizomes, keeping the
b" Tuberous roots ( dahlias ) - large bulb-like roots. Cut the roots apart
with a knife, leaving a piece of the original stem and a growth bud with each
How do I learn more?
Iowa State University offers a brochure listing dividing timetables for more
than 35 common perennials. Find the information at
www.extension.iastate.edu/pubs/ga.htm by clicking on No. RG-319, "When to
Clemson University extension has an online flier with detailed dividing
information based on root type. The pamphlet also offers additional
how to divide plants with large, heavy roots. The flyer can be found at
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